1. Field of the Invention
The present invention relates to a fuel cell stack including a stack body formed by stacking a plurality of power generation cells in a stacking direction. Each of the power generation cells includes an electrolyte electrode assembly and separators. The electrolyte electrode assembly includes a pair of electrodes and an electrolyte interposed between the electrodes. Power collecting terminals are provided at opposite ends of the stack body in the stacking direction. Further, the present invention relates to a method of producing the terminal of the fuel cell stack.
2. Description of the Related Art
For example, a solid polymer electrolyte fuel cell employs an electrolyte membrane (electrolyte). The electrolyte membrane is a polymer ion exchange membrane. A membrane electrode assembly (electrolyte electrode assembly) includes an anode, a cathode, and the electrolyte membrane interposed between the anode and the cathode. The membrane electrode assembly and separators sandwiching the membrane electrode assembly make up a unit of a fuel cell (power generation cell) for generating electricity. In use of the polymer electrolyte fuel cell, a predetermined number of power generation cells are stacked together to form a fuel cell stack.
In the fuel cell stack, normally, terminal plates, insulating plates, and end plates are provided at opposite ends of a stack body formed by stacking a plurality of power generation cells in the stacking direction. The terminal plates have power collecting terminals for collecting electrical energy from the stack body to the outside. The power collecting terminals are connected to a contactor (or a relay) to implement the ON/OFF control for supplying electrical energy to an external load such as a motor.
For example, in a terminal device of a fuel cell disclosed in Japanese Laid-Open Utility Model Publication No. 61-007868, as shown in FIG. 7, unit cells 1 and bipolar plates 2 are stacked alternately, and half plates 2a are provided at opposite ends in the stacking direction. Terminal plates 3 are provided outside the half plates 2a, and insulating plates 4 are provided outside the terminal plates 3. Further, end plates 5 are provided outside the insulating plates 4.
An electrode pole (power collecting terminal) 6 is electrically connected to each of the terminal plates 3. The electrode pole 6 passes through the insulating plate 4 and the end plate 5 to the outside. The electrode pole 6 is inserted into an insulating sleeve 7, and fixed through a nut 8.
However, in the above structure where the electrode pole 6 is simply connected to the terminal plate 3, the contact state tends to vary, and the current collection performance through the electrode pole 6 may be lowered undesirably. Further, since the electrode pole 6 is inserted into the insulating sleeve 7, and fixed through the nut 8, the assembling operation is laborious, and a large number of components are required.